Railway traffic controlling apparatus



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RAILWAY TRAFFIC CONTROLLING APPARATUS original Filed Juiy 25. 1930 2sheets-Sheet Km@ n .f N T .m @www m A IQ L e -1 n R www@ dlg, MIE Fl ummK. my M+ u www mum w12- I Nwrl Qblgw NNN Patented Nov. 1, 1932 Marianstares PATENr OFFICE RALPH R. KEMMERER, 0F SWISSVALE, PENSYLVANI,ASST'GNOR TQ UNIQN" SVVTGI-I & SIGNAL COMPANY, 0 SWISSVALE,PENNSYLVANIA, .A CORZPRATIN OF PENNSYLVANIA RAILWAY TRAFFICCONTRGLLING'APPARATUS Application flied July 23, 133), Serial No.469,941. Renewed February 26, 1932*.A

some remote point controls the movement-oi:

a railway switch and its associated signals, it is customary to provideapproach locking circuits, and to provide also means to check theintegrity of the approach locking circuits. In approach locking providedheretofore, a momentaryV loss of shunt in an ap.

preach track circuit or a momentary shortcircuiting of a detector trackcircuit may result in a loss of the approach locking, and such a losswill permit a switch to be reversed or to start to reverse in ront of anapproaching train,

In a despatcher control system, it is desirable to permit a route to beset up and the signals cleared, and to permit the despatcher to select areverse control circuit for a switch which will reverse the switchiininediately after a train has accepted the signais of the `first routeand cleared the detector track circuit. Such requirement makes itdesirable to provide a continuous check cn the approach locking toinsure that the switch does not prematurely operate. It is the purposeof my invention to provide a conrinuous check on the approach lockingcircnt and thereby prevent the loss of approach hgcking from occurring,and reduce to a minimum the possibility of a false operation of aswitch.

I will describe one form of apparatus einbodying my invention, and willthen point out the novel features thereof in claims.

Figs. l and 2 when placed end to end, with the Fig. l to the left, forma diagrammatic view of the apparatus embodying my invention when used inconnection with the op.-

eration of a single switch and its associated signals.

Referring to the drawings, a railway switch, designated bythe referencecharacter SW, is operated by a standard type of ei'fitcli machine, showninthe Fig, 2, by a symbol and designated by the reference char- SM. Theoperating circuits for thev switch machine SM are not shown in theiigure inasmuch Vas they form no part of my invention and may be any oneof several well known in the art. In this instance, the control of theswitch machine SM is by means ci despatcher controlled code relays to bereipeired'to later.

B means of insulated railjoints 3, the track` rails l and 2 are dividedinto track sections LST, L2T', 1T, RQT and' RST. `The track sectionsLST, LQT, RQT and RST will be referred to as approach sections, whilethe section 1T will be referred to as a detector track section. Eachtrack section is provided with a customary track circuit which includesa track battery and a track relay in a manner readily understood fromthe drawings. The wayside signals that govern traihc over the switch SWfrom the right to the left are designated by the reference 'character L,plus a numeral lto indicate the location, and the i wayside signalsgoverning trafIic from the left to the right are designated by thereference character R, plus a numeral to designate the location.Inasinuch as the operating circuits oi the signals form no part of myinvention, they are all omitted from the iigures for the sake ofclearness. It is thought that vthey would add nothing toL theunderstanding of my invention, andthat it is sucient to say that thesignals R3 and L3 are three-position signals, each capable of displayingproceed, caution and stop, that the signals RQa and L2@ are two-positionsignals, each capable of displaying proceed and stop, that the signalsRQcZ and L26 are two-position signals capable of displaying caution orstop, that the signals R20 and L20 are call-on signals, and that thesignal R25 is a lixed signa-l displaying stop only. In order to simplifythe iguressomewhat and to make them easier to understand, I have, inanumber of instances, placed a circuit controlling arinature in alocation that is not adjacent to the relay that controls the armature.In all such instances the armature is designated by a referencecharacter with an exponent corresponding to the reference character ot'the controlling relay and all such armatures are shown in their normalpositions. For illustration, the circuit controlling armature,designated by the reference character SSLM in the Fig. 1, is controlledby the relay LM of Fig. 2, and the armature normally occupies its raisedposition.

The despatcher controlled relays are shown in Fig. 2 located on a panelindicated by a dotted line FS. As the circuits for the control of thesedespatcher controlled relays also form no part et' my invention, theyare not shown on the figures, it being understood, however, that thedespatcher can elect to energize or deenergize these relays at will, and

that whenever a relay is energized, it lifts its armatures, and whendeenergized, its armatures drop to a down position. As a matter of fact,my invention is not limited to a despatcher controlled system 'for thecontrol of the switch, it being equally adaptable to remote controlledsystemsor to power interlocking systems.

The circuit controllers 4, 5 and 6 of Fig. 2 are operated by the' switchSW as indicated by a dotted line. Each controller occupies an upperposition indicated by a solid line when the switch is set for the maintrack, while each controller occupies a down position indicated by adotted line when the switch SW is set for a traliic movement to thesiding.

The switch control relay lV is a direct current polarized relay havingpolar armatures that remain in the position to which they were lastmoved by the energizing of the relay.

This relay lll, when energized with current of normal polarity, moves.its polar armatures to a normal position that selects the operatingcircuits (not shown) for the switch machine SM that results in theswitch SW7 being positioned for traitic on the main line. With currentor" reverse polarity supplied to the relay WV, then the polar armaturesare moved to a reverse position that selects the operating circuits forSM that result in the switch SW being` positioned for traiiic to thesiding. In Fig. 2, the normal position et the polar armatures et therelay `W is left-hand, as shown in the ligure, and the reverse positionis the right-hand position, that is, opposite trom that shown in theligure. The switch control relay W is controlled by despatchercontrolled relays Fcl/VS and NS. W ith normal relay 7bill/17S selectedby the despatcher, and its arn'iatures 9 and 10 raised, current suppliedto the relay lV by a circuit extending from battery terminal B alongwire 1l, armature 9, wire 12, relay W, wire 13, armature 14RM controlledby a relay RM of Fig. 1 and referred to later, wire 15, armature 1GLMcontrolled by a relay LM, wire 17, armature 13 et the traclr relay Tit,wire 19, armature 1G, and wire20 to common battery termi "l (l polarityof the current thus supplied movesl the polar armatures et relay W' tothe leitliand side and thus brings about the normal positioning' of theswitch Sli/V. Vith the despatcher selecting the reverse relay llilfd,current is supplied to the relay N from battery terminal B along wires11 and 21, armature 22, wire 23, arnfiature 1() ot :elav7 lll/VS in adown position, wire 19, armatur 18, wire 17, armature 16m, wire 15,armature 14R, wire 13, relay lff, wire 12, armature 9 in a downpesitien, wire 24, armature and wire 2O to common battery terminal C.The flew oi" current to rele" .7 this time is reversed and the pelarAannu -es reversed the righthand position with the result that theswitch @Vf is set for trahie to tne siding.

The switch controlled relay KR is a direct current polarized relay andis controlled jointly by the switch Sli? and the relay lll. l'Vith theswitch set in the normal position, and if' ay lll also in normalposition, the circuit to the relay ilconsists ot battery terminal ll,wire 2G, controller 4, wire 27, relay lill, wire 28, armature 3, wire2Q, centreller 6, and w' e 30 te commen battery terminal C. VJ 'uneswitch SW and at1 se position, then the reis.) 1 current from battery teach in revel sup 26 and 31, controller 5, wire 32,

Jtrec B along' wir es armature 3, wire 23, relay lili, wire 27,controller and wires 33 and 30 to common bat tery terminal C. llfith therelay energized coincidentally with the normal position ot the switchSi? and relay W', its` neutral armatures are raised and its polararmatures occupy the lett-hand position, while with the relay HRenergized with the switch Sllf and relay il] in reverse position, theneu` tral armatures et lil?. are raised and the polar armatures occupythe right-hand position.

The repeater relays NP and RP are con-. trolled jointly by the relayslilland W. The circuit iter the normal repeater relay lll" en` tendsfrom battery terminal B along arniature 7, wire 34, armature 35, polararmature 36, wire 37, armature 33, wire 39, relay il?, and to commonbattery terminal C. 'l` he circuit for energizing the reverse repeaterrelay RP extends trom battery terminal B along armature 7 in aright-hand position, wir-e 40, armatiue -l-l, polar armature 42 in arighthand position, wire 43, armature 44 in a down position, wire 45,relay lll), and to common battery terminal C.

The direction of tratlic over the switch SW is selected by thedirectional relays RH and LH, respectively. With the switch set for mainline trailic and the despatcher selecting` the relays RHS and XS on thepanel FS, we find that current is supplied from battery terminal B tothe relay RH over a circuit consisting of wires 11, 21 and 46, armature47 of a relay LHS, wire 48, armature 49 of relay RHS in its raisedposition, wire 50, armature f the relay XS in its raised position, wire59,

armature 59 of the relay YS, and wires 60 and to common battery terminalC. @nce the relay RH is energized, there is a path to common batteryterminal branching from the wire 55, along wire 61, armature 621m, wire63, armature 64 of the relay RH, and to coinmon battery terminalC. Inthe event the despatcher selects the relay LHS, While the i relay NWS isenergized to set the switch for the main line, relay XS is alsoenergized, and

we find that current will How to the directional relay LH from batteryterminal B, along wires 11, 21 and 46, armature 49 of relay RHS, wire48, armature 47 of relay LHS in a raised position, wire 65, armature663K, wire 200, coil of relay LH, wire 67, armature 54m, wire 55,armature 55NP, wire 56, armature 57 of the relay XS in a raisedposition, wire 58, armature 59, and wires 60 and 20 to common batteryterminal C.

While, with relay RWS energized so that the switch is set for thetraliic to the siding, the relay YS is energized when the despatcherselects the relay LHS, and we ind that the f relay LH is supplied withcurrent over the same circuit as just traced to the wire 55, then alongwire 61, armature 68M of the reverse relay RP, wire 69, armature 59 ofrelay YS,

wire 58, armature 57, and wires 60 and 20 to common battery terminal C.lith the relay LH once energized by either ofthe two above circuits, astick circuit to common battery terminal C is provided which includes airont contact of the relay as follows: From the '-0 wire 55 along wire61, armature 62KR of the KR relay, wire 70, armature 71 in a raisedposition, to common battery terminal C.

The directional relays RH and LH each control controlling relays that,in turn, gov- "15 ern operating circuits of wayside signals. Forexample, the operating circuits for thesignal R262 are controlled by therelay RcH and, in turn, this relay Rc1/,H is governed by the directionalrelay RH. Referring to i" 1, we find that the circuit for the relay RaHextends from battery terminal B at the righthand end of Fig. 1 alongarmature 7 2LGP of a relay LGP to be shortly described, wire 7 3,armature 74m, armature 7 5TE of a time element relay to be describedlater, armature 7 GKR, armature 7 7 RH in raised position, armature 7SRM in down position, armature 7 9KR,

armature S0RAS in down position, armature 81TR, armature .82LAS, wireV83, relay RaH,

" wire 84, armature 85 to a common battery terminal C. It is to be notedamong other things that in order to energize this controlling relay RaHso as to clear signal R2a, the opposing signal L2 must be set in thestop '53 position, the detector track circuit must be line, is alsocontrolled by the directional re.

lay RH. The circuit for relay RdH extends from the battery terminal B,shown at the right-hand end of Fig. 1, over the same circuit just traced`for relay RaH upto the polar armature 7 9K, then with armature 7 9KRreversed to the right-hand position, along armature 99m, armature100LAS, wire 101, relay ReZH, wires 102 and 84, and armature 85 tocommon battery terminal C. It is to be noted, therefore, that in orderto clear the signal R2cZ, the opposing signal L2 must be set atstop, thedetector track circuit :unoccupied, the switch SV reversed, and thedespatcher must select the directional relay RH. The signal L2@ iscontrolled by the controlling relay LaH which, in turn, is controlled bythe directional relay LH.V This time the circuit extends from thebattery terminal B, shown at the right-hand end of Fig. 1,alongvarmature SGRGP, armature77RH, armature 76KR, armature 7 5m,armature 7 4LH of the directional relay LH, wire 87, armature 88mdropped, armature 89M?s dropped, polar armature 90KR in the left-handposition, armature 91TR, armature 92RAS, wire 93, relay LaH, wire 94,and armature 95 to common battery terminal C. Thus to clear the signalL2a, it requires that the opposing signals be set at stop, the detectortrack circuit unoccupied, the switch SW set normal, and the despatcherselects the directional relay LH. The signal L25 is controlled by thecontrolling relay LJH which is energized by a circuit that extendsfron'i the battery terminal B over the same circuit just traced forrelay LaH up to the point of the polar armature 90m, then with thearmature 90KR reversed, to the right-hand position, along armature 96TH,wire 97, relayLH, wires 98 and 94,*and armature 95 to common batteryterminal C.

The .callon signal R20 is governed by a controlling relay RcH, and thisrelay RGH is,

102 and 84, and armature 85 to common bat- Y tery terminal C. It followsthat in order to Y clear the call-on signal R20, the despatcher must notonly select the directional relay RH by energizing the relay RHS but hemust, in addition, energize the relay CH. The callon signal vL20 isgoverned by a controlling -i stood from the Fig. 2, and

relay LCH, which has an energizing circuit which extends from batteryterminal B over the same circuit as traced or'the relay LaH upto andincluding armature SQLAS, then along wire 110, armature 111 of relay CH,wire 112, armature 118, wire 114, armature 115', Wire 116, coil of relayLCH, wires 117, 98 and 911, and armature 95 to common battery terminalC. y 1

Associated with the controlling relays RaH, BGH and RCZH is a relay RG?,which has an energizing circuit extending from battery terminal B, alongarmature 118 ot relay RCZH, armature 119 of relay BGH, armature 120 ofrelay Rall, wire 121, coil of relay BGP to common battery terminal C.This relay BGP by being energized when its associated relays aredeenergized, checks the stop position of each of the R2 signals. 1Likewise, associated with the controlling relays Loli, LZJH and LCH is arelay LGF, and a circuit tor energizing this relay LG? includes anarmature of each of these controlling relays in a down position as willbe readily underit therefore checks the stop position of signal L2.

The signal R3 is controlled by a track relay R2TR and a line relay RD.The controlling circuit for the line relay RD is not shown in the Fig.and it is to be understood that it is in accordance with well knownstandard practice. The control of the distant signal L3 is by atrackrelay L2TR and a line relay Ll), `and the control of this linerelay LD will be in a manner similar to that used for controlling therelay RD.

For each direction of trailic there is provided an approachlocking stickrelay and an approach control stick relay. rlhe approach locking stickrelay RM is associated with trailic moving from the left to the riohtand is normally energized by stick circuit ei;- tending from the batteryterminal B located at signal R8 along armature 126 in a down position,wire 127, armature 128V of relay BGP, wire 129, armature 130 ofdirectional relay RH, wire 186, armature 137 of the relay RM, coil ofrelay RM, and to common battery terminal C. Extending around the frontcontact of armature 187 is a shunt circuit consisting of Wire 1.81,branching from wire 136, armature 132KR, wire 183, armature 181i of theapproach control relay RAS about to be described, wire 135, coil ofrelay RM, and to common battery terminal C, and vin addition to thisshunt path around the front contact of armature 187, there is a secondshunt path branching from wire 181 and extending along wire 188,armature 189TL of the time element relay TE, wires 1410 and 185, coilor' relay RM, and to common battery terminal C. It will be noted,therefore, that the approach locking relay RM will be deenergized by thedespatcher selecting the directional relay RH, and that with relay RMonce deenergized, it

Yand to common battery terminal.

can bel reenergized only with the approach control relay RAS up, or inthe event the time elementrelay TE has acted to close the armature1,89TE in amanner to be described later.

Approach .control stick relay RAS is normally energized by a stickcircuit extending from battery terminal B, shown at the lefthand end ofFie'. 1, along wire 141, armature 142 oi' the track relay BSTR, armature148 t the track relay R2TR, wire 1114, coil of relay BAS, wire 145, itsown armature 1&6, and to common battery terminal C. There are providetwo by-paths around the front contact ci armature 146, one of whichextends along wire 147, from the coil of relay RAS, armature 148 ol thedirectional relay RH, and to common battery terminal C, while the secondlay-path entends from wire 147, along wire 149, a polar armature 150KRof the KR lay, and to common battery terminal C. hus, it will beobserved that with a train )preaching the switch SW' from the left andcupying either ci' the track sections K8T or m21 the holding circuit forthe BAS relay will be opened, and that with relay RAS once deenergized,it can be reenergized only when these track sections are vacated and thedirectional ion i relay .-l-l is down, or instead of l relay lll-l beingdown, the switch ersed so as to cause the polar arma- 150m to bereversed.

Asso -iated with trai'lie moving from the right to the left is anapproach locking stick relay and an approach control stick relay 1 LAS.The approach locking relay LM is normally energized and has anenergizing stick circuit similar tothat traced for the approach lockingrelay BM, and which ententes from battery terminal 13, along armature151 of line relay Ll), wire 152, armature 158 oi' relay LG?, wire 154,armature o the directional relay LH, wire 159, its own armature 166,coil of relay LM, and to co1 nnon battery terminal C. Around the frontContact oi' armature is a shunt path branchin l'rom wire 159 andextending along wire 156, armature 157 of the approach control relay l,'1S in raised position, wire 158, coil of relay l it. second by-patharound the front contact of armature 160 extends from wire 159 alongwire 161, armature 162TE of the time element relay TW, coil or relay LMand to common battery terminal. r1`he approach control stick relay LASis normally energized by a stick circuit similar to that traced for theapproach relay l-l-S, and which starts at battery terminal B shown atthe extreme right-hand end of Fig. 2, and extends along wire 168,armature 16d of the track relay L'ST., armature 165 ot track relay L2TR,wire 166, coil of relay LAS, wire 167, its own armature 168, and tocommon battery terminal C. Around the front contact of the armature 168is a shunt path branchingfrom wire 167, and extending along wire 169,armature 170 of the directional relay LH, and to common battery terminalC.

Associated with the control of the approach locking relays RM and LM isa time element relay TE. This time element relay TE may be any of thewell known types and is arranged to close its contacts a predeterminedtime interval after its energizing circuit has been closed. LookingatPig. 2, we lind the energizing circuit for the relay TE extends frombatteryterminal B, along armature 171 of a relay MP, wire 172, armature173m, armature 174LH, armature 175RH, coil of TE, and to common batteryterminal C. Thus for the time element relay TE to function, it requiresthat the MP relay be energized, that the detector track section 1T beunoccupied, and that both directional relays LII and RH be down.v Therelay MP, which controls the supply of current to relay TE is energizedby either one of two circuits. The rst circuit extends from the batteryterminal B, located at signal R3, along armature 126, wire 127, armature128, wire 129, armature 130, wire 136, armature 137 in a down position,wire 176, coil of MP, and to common battery .terminal C. The secondcircuit for energizing relay MP receives energy at battery terminal Blocated at signal L3 and extends along armature 151, wire 152, armature153, wire 154, armature 155, wire 159, armature 160 in a down position,wire 177, coil of MP, and to common battery terminal C.

I will now describe the operation of the approach locking, and willassume that the despatcher has selected the relay RHS and that energyhas been supplied to the directional relay RH to lift the armature 130.Upon armature 130 being raised, the approach locking relay RM becomesdeenergized opening its front contacts and closing its back contacts. Itwill thus `be seen that, after the despatcher has cleared Athe signalR2@ by energizing the rela-y RII the approach locking relay RM isdeenergized and the circuit for the switch control'relay W is opened atthe armature 14RM of the approachlocking relay RM. It follows then thatitis safe for the despatcher to select the reverse position of theswitch SWY by deenergizing the normal relay NWS and energizing`thereverse relay RWS, in view of the fact that as long as relay RM isdeenergized, since the relay IV is of a type which will remain in theposition to which it was last moved, the

switch S'W will not follow the energizing of relay RWS. The relay W willrespond to the energizing of the despatcher relay RWS only when itscontrolling circuit has been closed at armature 14RM which can takeplace only when the approach locking relay RM is reenergized.

I will next assume that a train approaches signal R2 after the signalhas beencleared. It is evident that if the track relay TR is momentarilyshort-circuited, under these conditions, so as to drop the directionalrelay RH, thereby permitting relay RGP to pick "5 up, the approachlocking relay RM will. still remain deenergized due to its stickcircuit. It follows that a momentary short circuit of the detector tracksection does not, with my invention, permit a loss of Vthe approach "71locking. y

VAgain it is to be noted, that after the despatcher has selected trallicfrom the left to the right and energy has been supplied to the Mdirectional relay RH, then as soon as a train enters the first approachtrack section RBT, the circuit for the approach control stick relay RASis opened, and the relay RAS becomes deenergized. Relay RAS will then^J35 remain deenergized even though the loss of shunt occurs on eithertrack relay RSTR or R2TR during the time a train occupies the tracksections, RST or R2T, or inthe event either relay is picked up by aforeign cur-7,90 rent. Relay RAS remains deenergized due to the factthat to reenergize the relay, the by-path around the stick armature 146must be closed, and to close this by-path requires that the directionalrelay RH be deenergizech A so that the armature 148 is in engagementwith its back contact. With relay RH deenergized and the train vacatingthe track sections RST and R2T, the pick-up circuit for the rela-y RASis closed and the relay re, 100 stored to its normal position. lith thestick" relay RAS thus restored so as to close the front contact ofarmature 134, the relay RM is restored to its normal position.Therefore, the two stick relays RM and RAS provide a combination thatcontinuously checks thel integrity of the approach locking and insures aminimum chance of a false operation of the switch SW occurring. Theapproach locking relay LM and its companion relay LAS pro- Vide acontinuous check on the approach locking for traic moving from the rightto the left in the same manner as relays RM and RAS provide a continuouscheck on the approach locking for traflic moving from the k.115 left tothe right.

It is to be noted that the second by-path around the front contact ofarmature 146 of the relay RAS, and which by-path includes the polararmature 150KR reversed to a 120 right-handY position, provides a meansforV retaining the relay RAS in an energized condition whenever theswitch SIN is set for traffic from the siding, even though one or bothof the approach track sections RTand R2T have been occupied and thenlater vacated.

In the event that a route has been set up and a train has entered anapproach track section of the route and it becomes necessary to changethe position of the switch before the train passes beyond the limits of'the route,

has cleared signal R2@ and a train has entered track section RQTtraveling toward the signal and that it then becomes necessary to stopthis train and to reverse the switch. The 'despatcher by deenergizingrelay RI-I sets signal RfZa at stop and with relay RII down, the relayMP is energized by the circuit previously pointed out and with. relay MPup, the Ytime element relay TE is energized to start its operation.

After a predetermined time interval, relay TE closes its contacts, thistime interval being chosen of sufficient length that the approachingtrain can come to a stop to the rear of the signal E2G. With relay TEclosing its contacts, the pick-up circuit for approach locking relay RM,which includes armature 139TE is closed, and the relay RM is therebyreenergized, with the result that the switch can be reversed in theusual manner. It will be understood that time element relay TE functionsin a like manner for a train approaching signal L2.

Although I have herein shown and described only one form of railwaytraffic controlling apparatus embodying my invention, it is understoodthat various changes and modifications may be made therein within thescope of the appended claims without departing from the spirit and scopeof my invention.

Having thus described my invention, what I claim is:

1. In combination, a railway switch, a

first track section remote from the switch, a second track sectionadjacent to the switch, an approach control relay, a normally closedAstick circuit to normally energize said relay, a track relay for saidfirst track section to rupture the stick circuit in response to a trainin said first track section, a track relay for said second tracksection, a trafiic governing relay controlled by the track relay of thesecond track section arranged to` be deenergized in response to a trainin said second track section, arplck-up circuit for 1 said approachcontrol relay effective to reenergize said approach contro-l relay whenthe track relay of the first track `section is energized and the trafficgoverning'relay is deenergized, and means to control the operation ofthe switch rendered effective with said.

approach control relay energized.

2. In combination, a railway switch, a first and a second approach trackcircuits, a detector track circuit, an approach control relay, anormally closed stick circuit for normally energizing said relay, meanscontrolled by the first and second approach track circuits to rupturethe said stick circuit in response to a train occupying either of saidapproach track circuits, a pick-up circuit for said relay renderedeffective to energize said relay when said first and second approachtrack circuits are both unoccupied by a train and the detector trackcircuit is occupied by a train, and means to control the operation ofthe switch rendered effective when -rection governed by said directionalrelay,

means active when said control relay is once deenergized to retain saidrelay deenergized as long as said track circuit is occupied or the saiddirectional relay energized, and circuit means to control the operationof the switchv rendered ineffective as long as said approach controlrelay remains deenergized.

4. In combination, a railway switch, a first relay normally energized, asecond relay nor` mally energized, a trafhc governing` relay to governtrafficover the switch and adapted when set to permit traffic to moveover the switch to deenergize said first relay, a track circuit remotefrom the switch adapted when occupied to deenergize said second relay,

means to prevent the reenergizing of the first Yrelay until the secondrelay is energized,

means to prevent the reenergizing of the second relay as long as thetrack circuit is occupied or the traffic governing relay set toV permittrafiic over the switch, and a circuit to control the operation of theswitch rendered ineffective as long as the Erst relay remainsdeenergized.

5. In'combination, a railway switch, a first.

stick relay, a normally closed stick circuit for said relay, a. secondstick relay, a normally closed circuit for said second relay, a trafficgoverning relay adapted when set to permit trafiic to move over theswitch to open the stick circuit for the first stick relay, a trackcircuit remote from the switch adapted when occupied to open the stickcircuit for the second stick relay, a pick-up circuit for the firststick relay closed when the second stick relay is energized, a pick-upcircuit for said second stick relay closed, when said track circuit isunoccupied and the traffic governing relay set to stop traffic, and acircuit to control the operation of the switch rendered ineffective aslong as the first stick relay remains deenergized.

6. In combination, a railway switch, manual controlled relays to controlthe operation of the switch, a signaling means to govern traffic overthe switch, a track circuit, an apisa proach locking stick relay, anormally closed stick circuit to energize said relay, adapted to beruptured by the signaling means cleared to permit a train to move overthe switch, an

f approach control stick relay, a normally closed stick circuit toenergize said relay and adapted to be ruptured in response to a. trainentering the track circuit, a pick-up circuit for the approach lockingstick relay controlled by said approach control stick relay, a pick-upcircuit for the approach control stick relay eiiective to energize said-relay only after the track circuit has been vacated by the train andthe signaling` means set to stop traffic, and mea-ns controlled by theapproach locking stick relay to render said manually controlled relaysineffective to control the switch as long as said approach locking relayremains deenergized.

7. In combination, a single track railway, a switch for said railway, anormally energized approach control relay associated with each directionof traliic over the switch, a normally closed stick circuit for eachapproach control relay, means responsive to a train approaching1 theswitch to rupture the stick circuit or the approach control relayassociated with the same direction of trallic as that in which the trainapproaches the switch,

and a signaling circuit for each direction oftraiiic, each signalingcircuit including a front Contact of the approach control relayassociated with the opposing direction of traffic and a back contact ofthe approach control relay associated with the same direction of trafficas the said signaling circuit.

S. In combination, a railway switch having a normal and a reverseposition, a normal Y locking relay deenergized in response to theclosing of the signaling circuit to render ineffective the despatcherscontrol over the reverse control circuit of the switch, a normallyenergized approach control relay deenergized in response to a trainentering the approach track section to retain said approach lockingrelay deenergized, and means rendered active by the train successivelytraveling through the approach and detector track sections to reenergizesaid approach control relay and in turn the approach locking relay tothereby restore the despatchers control over the reverse control circuitof the switch.

9. In combination, a railway track switch, a signal forgoverning tratlicmovements in a given direction over said switch, a signal relay, acircuit including a Jfront contact of said relay for controlling saidsignal, an approach locking relay, a stick circuit for said approachlocking relay including a back contact of said signal relay, an approachstick relay, a stick circuit for said approach stick relay controlled bya train approaching said signal in said given direction, a pickupcircuit for said approach stick relay including a back Contact of saidsignal relay, a pick-up circuit for said approach locking relayincluding a front contact of said approach stick relay, and meanscontrolled by said approach locking relay for controlling said switch.

10. In combina-tion, a railway track switch, a signal for governingtraliic movements in a given direction over said switch, means forcontrolling said signal, an approach locking relay, a stick circuit forsai-d approach locking relay closed only if said signal is controlled toindicate stop, an approach stick relay, a stick circuit for saidapproach stick relay which becomes deenergized if a train approachessaid signal in said given direction, a pickup circuit for said approachstick relay closed only if said signal is controlled to indicate stop, apickup circuit for said approach locking relay controlled by saidapproach stick relay, and means controlled by said approach Vlockingrelay for controlling said switch.

In testimony whereof I aiiX my signature.

RALPH R. KEMMERER.

